Amateur footage posted online on Thursday purports to show the aftermath of the strikeAt least 28 people are reported to have been killed in an air strike on a refugee camp in rebel-held northern Syria, monitors say.

Images on social media showed tents destroyed at the Kamouna camp near Sarmada in Idlib province, close to the Turkish border.

Some reports say the attack was by Syrian or Russian warplanes but this has not been confirmed.

The strike comes a day after the extension of a truce was confirmed.

The Syrian military and non-jihadist rebel forces had agreed to a temporary truce around the the city of Aleppo, following pressure from the US and Russia

A nationwide cessation of hostilities has been in place since February, but it has come under severe pressure recently, particularly around Aleppo, where some 300 people have died in clashes over the past two weeks.

The UN has warned that if the nationwide cessation fails, it will be "catastrophic" and could send 400,000 more people heading for refuge at the border with Turkey.

Smouldering ground

The Kamouna camp for the internally displaced is about 4km from Sarmada and 10km from the Turkish border.